Java example source code file (space.cpp)
The space.cpp Java example source code/*
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* DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
*
* This code is free software; you can redistribute it and/or modify it
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* published by the Free Software Foundation.
*
* This code is distributed in the hope that it will be useful, but WITHOUT
* ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
* FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
* version 2 for more details (a copy is included in the LICENSE file that
* accompanied this code).
*
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* 2 along with this work; if not, write to the Free Software Foundation,
* Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
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#include "precompiled.hpp"
#include "classfile/systemDictionary.hpp"
#include "classfile/vmSymbols.hpp"
#include "gc_implementation/shared/liveRange.hpp"
#include "gc_implementation/shared/markSweep.hpp"
#include "gc_implementation/shared/spaceDecorator.hpp"
#include "memory/blockOffsetTable.inline.hpp"
#include "memory/defNewGeneration.hpp"
#include "memory/genCollectedHeap.hpp"
#include "memory/space.hpp"
#include "memory/space.inline.hpp"
#include "memory/universe.inline.hpp"
#include "oops/oop.inline.hpp"
#include "oops/oop.inline2.hpp"
#include "runtime/java.hpp"
#include "runtime/safepoint.hpp"
#include "utilities/copy.hpp"
#include "utilities/globalDefinitions.hpp"
#include "utilities/macros.hpp"
void SpaceMemRegionOopsIterClosure::do_oop(oop* p) { SpaceMemRegionOopsIterClosure::do_oop_work(p); }
void SpaceMemRegionOopsIterClosure::do_oop(narrowOop* p) { SpaceMemRegionOopsIterClosure::do_oop_work(p); }
HeapWord* DirtyCardToOopClosure::get_actual_top(HeapWord* top,
HeapWord* top_obj) {
if (top_obj != NULL) {
if (_sp->block_is_obj(top_obj)) {
if (_precision == CardTableModRefBS::ObjHeadPreciseArray) {
if (oop(top_obj)->is_objArray() || oop(top_obj)->is_typeArray()) {
// An arrayOop is starting on the dirty card - since we do exact
// store checks for objArrays we are done.
} else {
// Otherwise, it is possible that the object starting on the dirty
// card spans the entire card, and that the store happened on a
// later card. Figure out where the object ends.
// Use the block_size() method of the space over which
// the iteration is being done. That space (e.g. CMS) may have
// specific requirements on object sizes which will
// be reflected in the block_size() method.
top = top_obj + oop(top_obj)->size();
}
}
} else {
top = top_obj;
}
} else {
assert(top == _sp->end(), "only case where top_obj == NULL");
}
return top;
}
void DirtyCardToOopClosure::walk_mem_region(MemRegion mr,
HeapWord* bottom,
HeapWord* top) {
// 1. Blocks may or may not be objects.
// 2. Even when a block_is_obj(), it may not entirely
// occupy the block if the block quantum is larger than
// the object size.
// We can and should try to optimize by calling the non-MemRegion
// version of oop_iterate() for all but the extremal objects
// (for which we need to call the MemRegion version of
// oop_iterate()) To be done post-beta XXX
for (; bottom < top; bottom += _sp->block_size(bottom)) {
// As in the case of contiguous space above, we'd like to
// just use the value returned by oop_iterate to increment the
// current pointer; unfortunately, that won't work in CMS because
// we'd need an interface change (it seems) to have the space
// "adjust the object size" (for instance pad it up to its
// block alignment or minimum block size restrictions. XXX
if (_sp->block_is_obj(bottom) &&
!_sp->obj_allocated_since_save_marks(oop(bottom))) {
oop(bottom)->oop_iterate(_cl, mr);
}
}
}
// We get called with "mr" representing the dirty region
// that we want to process. Because of imprecise marking,
// we may need to extend the incoming "mr" to the right,
// and scan more. However, because we may already have
// scanned some of that extended region, we may need to
// trim its right-end back some so we do not scan what
// we (or another worker thread) may already have scanned
// or planning to scan.
void DirtyCardToOopClosure::do_MemRegion(MemRegion mr) {
// Some collectors need to do special things whenever their dirty
// cards are processed. For instance, CMS must remember mutator updates
// (i.e. dirty cards) so as to re-scan mutated objects.
// Such work can be piggy-backed here on dirty card scanning, so as to make
// it slightly more efficient than doing a complete non-detructive pre-scan
// of the card table.
MemRegionClosure* pCl = _sp->preconsumptionDirtyCardClosure();
if (pCl != NULL) {
pCl->do_MemRegion(mr);
}
HeapWord* bottom = mr.start();
HeapWord* last = mr.last();
HeapWord* top = mr.end();
HeapWord* bottom_obj;
HeapWord* top_obj;
assert(_precision == CardTableModRefBS::ObjHeadPreciseArray ||
_precision == CardTableModRefBS::Precise,
"Only ones we deal with for now.");
assert(_precision != CardTableModRefBS::ObjHeadPreciseArray ||
_cl->idempotent() || _last_bottom == NULL ||
top <= _last_bottom,
"Not decreasing");
NOT_PRODUCT(_last_bottom = mr.start());
bottom_obj = _sp->block_start(bottom);
top_obj = _sp->block_start(last);
assert(bottom_obj <= bottom, "just checking");
assert(top_obj <= top, "just checking");
// Given what we think is the top of the memory region and
// the start of the object at the top, get the actual
// value of the top.
top = get_actual_top(top, top_obj);
// If the previous call did some part of this region, don't redo.
if (_precision == CardTableModRefBS::ObjHeadPreciseArray &&
_min_done != NULL &&
_min_done < top) {
top = _min_done;
}
// Top may have been reset, and in fact may be below bottom,
// e.g. the dirty card region is entirely in a now free object
// -- something that could happen with a concurrent sweeper.
bottom = MIN2(bottom, top);
MemRegion extended_mr = MemRegion(bottom, top);
assert(bottom <= top &&
(_precision != CardTableModRefBS::ObjHeadPreciseArray ||
_min_done == NULL ||
top <= _min_done),
"overlap!");
// Walk the region if it is not empty; otherwise there is nothing to do.
if (!extended_mr.is_empty()) {
walk_mem_region(extended_mr, bottom_obj, top);
}
// An idempotent closure might be applied in any order, so we don't
// record a _min_done for it.
if (!_cl->idempotent()) {
_min_done = bottom;
} else {
assert(_min_done == _last_explicit_min_done,
"Don't update _min_done for idempotent cl");
}
}
DirtyCardToOopClosure* Space::new_dcto_cl(ExtendedOopClosure* cl,
CardTableModRefBS::PrecisionStyle precision,
HeapWord* boundary) {
return new DirtyCardToOopClosure(this, cl, precision, boundary);
}
HeapWord* ContiguousSpaceDCTOC::get_actual_top(HeapWord* top,
HeapWord* top_obj) {
if (top_obj != NULL && top_obj < (_sp->toContiguousSpace())->top()) {
if (_precision == CardTableModRefBS::ObjHeadPreciseArray) {
if (oop(top_obj)->is_objArray() || oop(top_obj)->is_typeArray()) {
// An arrayOop is starting on the dirty card - since we do exact
// store checks for objArrays we are done.
} else {
// Otherwise, it is possible that the object starting on the dirty
// card spans the entire card, and that the store happened on a
// later card. Figure out where the object ends.
assert(_sp->block_size(top_obj) == (size_t) oop(top_obj)->size(),
"Block size and object size mismatch");
top = top_obj + oop(top_obj)->size();
}
}
} else {
top = (_sp->toContiguousSpace())->top();
}
return top;
}
void Filtering_DCTOC::walk_mem_region(MemRegion mr,
HeapWord* bottom,
HeapWord* top) {
// Note that this assumption won't hold if we have a concurrent
// collector in this space, which may have freed up objects after
// they were dirtied and before the stop-the-world GC that is
// examining cards here.
assert(bottom < top, "ought to be at least one obj on a dirty card.");
if (_boundary != NULL) {
// We have a boundary outside of which we don't want to look
// at objects, so create a filtering closure around the
// oop closure before walking the region.
FilteringClosure filter(_boundary, _cl);
walk_mem_region_with_cl(mr, bottom, top, &filter);
} else {
// No boundary, simply walk the heap with the oop closure.
walk_mem_region_with_cl(mr, bottom, top, _cl);
}
}
// We must replicate this so that the static type of "FilteringClosure"
// (see above) is apparent at the oop_iterate calls.
#define ContiguousSpaceDCTOC__walk_mem_region_with_cl_DEFN(ClosureType) \
void ContiguousSpaceDCTOC::walk_mem_region_with_cl(MemRegion mr, \
HeapWord* bottom, \
HeapWord* top, \
ClosureType* cl) { \
bottom += oop(bottom)->oop_iterate(cl, mr); \
if (bottom < top) { \
HeapWord* next_obj = bottom + oop(bottom)->size(); \
while (next_obj < top) { \
/* Bottom lies entirely below top, so we can call the */ \
/* non-memRegion version of oop_iterate below. */ \
oop(bottom)->oop_iterate(cl); \
bottom = next_obj; \
next_obj = bottom + oop(bottom)->size(); \
} \
/* Last object. */ \
oop(bottom)->oop_iterate(cl, mr); \
} \
}
// (There are only two of these, rather than N, because the split is due
// only to the introduction of the FilteringClosure, a local part of the
// impl of this abstraction.)
ContiguousSpaceDCTOC__walk_mem_region_with_cl_DEFN(ExtendedOopClosure)
ContiguousSpaceDCTOC__walk_mem_region_with_cl_DEFN(FilteringClosure)
DirtyCardToOopClosure*
ContiguousSpace::new_dcto_cl(ExtendedOopClosure* cl,
CardTableModRefBS::PrecisionStyle precision,
HeapWord* boundary) {
return new ContiguousSpaceDCTOC(this, cl, precision, boundary);
}
void Space::initialize(MemRegion mr,
bool clear_space,
bool mangle_space) {
HeapWord* bottom = mr.start();
HeapWord* end = mr.end();
assert(Universe::on_page_boundary(bottom) && Universe::on_page_boundary(end),
"invalid space boundaries");
set_bottom(bottom);
set_end(end);
if (clear_space) clear(mangle_space);
}
void Space::clear(bool mangle_space) {
if (ZapUnusedHeapArea && mangle_space) {
mangle_unused_area();
}
}
ContiguousSpace::ContiguousSpace(): CompactibleSpace(), _top(NULL),
_concurrent_iteration_safe_limit(NULL) {
_mangler = new GenSpaceMangler(this);
}
ContiguousSpace::~ContiguousSpace() {
delete _mangler;
}
void ContiguousSpace::initialize(MemRegion mr,
bool clear_space,
bool mangle_space)
{
CompactibleSpace::initialize(mr, clear_space, mangle_space);
set_concurrent_iteration_safe_limit(top());
}
void ContiguousSpace::clear(bool mangle_space) {
set_top(bottom());
set_saved_mark();
CompactibleSpace::clear(mangle_space);
}
bool ContiguousSpace::is_in(const void* p) const {
return _bottom <= p && p < _top;
}
bool ContiguousSpace::is_free_block(const HeapWord* p) const {
return p >= _top;
}
void OffsetTableContigSpace::clear(bool mangle_space) {
ContiguousSpace::clear(mangle_space);
_offsets.initialize_threshold();
}
void OffsetTableContigSpace::set_bottom(HeapWord* new_bottom) {
Space::set_bottom(new_bottom);
_offsets.set_bottom(new_bottom);
}
void OffsetTableContigSpace::set_end(HeapWord* new_end) {
// Space should not advertize an increase in size
// until after the underlying offest table has been enlarged.
_offsets.resize(pointer_delta(new_end, bottom()));
Space::set_end(new_end);
}
#ifndef PRODUCT
void ContiguousSpace::set_top_for_allocations(HeapWord* v) {
mangler()->set_top_for_allocations(v);
}
void ContiguousSpace::set_top_for_allocations() {
mangler()->set_top_for_allocations(top());
}
void ContiguousSpace::check_mangled_unused_area(HeapWord* limit) {
mangler()->check_mangled_unused_area(limit);
}
void ContiguousSpace::check_mangled_unused_area_complete() {
mangler()->check_mangled_unused_area_complete();
}
// Mangled only the unused space that has not previously
// been mangled and that has not been allocated since being
// mangled.
void ContiguousSpace::mangle_unused_area() {
mangler()->mangle_unused_area();
}
void ContiguousSpace::mangle_unused_area_complete() {
mangler()->mangle_unused_area_complete();
}
void ContiguousSpace::mangle_region(MemRegion mr) {
// Although this method uses SpaceMangler::mangle_region() which
// is not specific to a space, the when the ContiguousSpace version
// is called, it is always with regard to a space and this
// bounds checking is appropriate.
MemRegion space_mr(bottom(), end());
assert(space_mr.contains(mr), "Mangling outside space");
SpaceMangler::mangle_region(mr);
}
#endif // NOT_PRODUCT
void CompactibleSpace::initialize(MemRegion mr,
bool clear_space,
bool mangle_space) {
Space::initialize(mr, clear_space, mangle_space);
set_compaction_top(bottom());
_next_compaction_space = NULL;
}
void CompactibleSpace::clear(bool mangle_space) {
Space::clear(mangle_space);
_compaction_top = bottom();
}
HeapWord* CompactibleSpace::forward(oop q, size_t size,
CompactPoint* cp, HeapWord* compact_top) {
// q is alive
// First check if we should switch compaction space
assert(this == cp->space, "'this' should be current compaction space.");
size_t compaction_max_size = pointer_delta(end(), compact_top);
while (size > compaction_max_size) {
// switch to next compaction space
cp->space->set_compaction_top(compact_top);
cp->space = cp->space->next_compaction_space();
if (cp->space == NULL) {
cp->gen = GenCollectedHeap::heap()->prev_gen(cp->gen);
assert(cp->gen != NULL, "compaction must succeed");
cp->space = cp->gen->first_compaction_space();
assert(cp->space != NULL, "generation must have a first compaction space");
}
compact_top = cp->space->bottom();
cp->space->set_compaction_top(compact_top);
cp->threshold = cp->space->initialize_threshold();
compaction_max_size = pointer_delta(cp->space->end(), compact_top);
}
// store the forwarding pointer into the mark word
if ((HeapWord*)q != compact_top) {
q->forward_to(oop(compact_top));
assert(q->is_gc_marked(), "encoding the pointer should preserve the mark");
} else {
// if the object isn't moving we can just set the mark to the default
// mark and handle it specially later on.
q->init_mark();
assert(q->forwardee() == NULL, "should be forwarded to NULL");
}
compact_top += size;
// we need to update the offset table so that the beginnings of objects can be
// found during scavenge. Note that we are updating the offset table based on
// where the object will be once the compaction phase finishes.
if (compact_top > cp->threshold)
cp->threshold =
cp->space->cross_threshold(compact_top - size, compact_top);
return compact_top;
}
bool CompactibleSpace::insert_deadspace(size_t& allowed_deadspace_words,
HeapWord* q, size_t deadlength) {
if (allowed_deadspace_words >= deadlength) {
allowed_deadspace_words -= deadlength;
CollectedHeap::fill_with_object(q, deadlength);
oop(q)->set_mark(oop(q)->mark()->set_marked());
assert((int) deadlength == oop(q)->size(), "bad filler object size");
// Recall that we required "q == compaction_top".
return true;
} else {
allowed_deadspace_words = 0;
return false;
}
}
#define block_is_always_obj(q) true
#define obj_size(q) oop(q)->size()
#define adjust_obj_size(s) s
void CompactibleSpace::prepare_for_compaction(CompactPoint* cp) {
SCAN_AND_FORWARD(cp, end, block_is_obj, block_size);
}
// Faster object search.
void ContiguousSpace::prepare_for_compaction(CompactPoint* cp) {
SCAN_AND_FORWARD(cp, top, block_is_always_obj, obj_size);
}
void Space::adjust_pointers() {
// adjust all the interior pointers to point at the new locations of objects
// Used by MarkSweep::mark_sweep_phase3()
// First check to see if there is any work to be done.
if (used() == 0) {
return; // Nothing to do.
}
// Otherwise...
HeapWord* q = bottom();
HeapWord* t = end();
debug_only(HeapWord* prev_q = NULL);
while (q < t) {
if (oop(q)->is_gc_marked()) {
// q is alive
// point all the oops to the new location
size_t size = oop(q)->adjust_pointers();
debug_only(prev_q = q);
q += size;
} else {
// q is not a live object. But we're not in a compactible space,
// So we don't have live ranges.
debug_only(prev_q = q);
q += block_size(q);
assert(q > prev_q, "we should be moving forward through memory");
}
}
assert(q == t, "just checking");
}
void CompactibleSpace::adjust_pointers() {
// Check first is there is any work to do.
if (used() == 0) {
return; // Nothing to do.
}
SCAN_AND_ADJUST_POINTERS(adjust_obj_size);
}
void CompactibleSpace::compact() {
SCAN_AND_COMPACT(obj_size);
}
void Space::print_short() const { print_short_on(tty); }
void Space::print_short_on(outputStream* st) const {
st->print(" space " SIZE_FORMAT "K, %3d%% used", capacity() / K,
(int) ((double) used() * 100 / capacity()));
}
void Space::print() const { print_on(tty); }
void Space::print_on(outputStream* st) const {
print_short_on(st);
st->print_cr(" [" INTPTR_FORMAT ", " INTPTR_FORMAT ")",
bottom(), end());
}
void ContiguousSpace::print_on(outputStream* st) const {
print_short_on(st);
st->print_cr(" [" INTPTR_FORMAT ", " INTPTR_FORMAT ", " INTPTR_FORMAT ")",
bottom(), top(), end());
}
void OffsetTableContigSpace::print_on(outputStream* st) const {
print_short_on(st);
st->print_cr(" [" INTPTR_FORMAT ", " INTPTR_FORMAT ", "
INTPTR_FORMAT ", " INTPTR_FORMAT ")",
bottom(), top(), _offsets.threshold(), end());
}
void ContiguousSpace::verify() const {
HeapWord* p = bottom();
HeapWord* t = top();
HeapWord* prev_p = NULL;
while (p < t) {
oop(p)->verify();
prev_p = p;
p += oop(p)->size();
}
guarantee(p == top(), "end of last object must match end of space");
if (top() != end()) {
guarantee(top() == block_start_const(end()-1) &&
top() == block_start_const(top()),
"top should be start of unallocated block, if it exists");
}
}
void Space::oop_iterate(ExtendedOopClosure* blk) {
ObjectToOopClosure blk2(blk);
object_iterate(&blk2);
}
HeapWord* Space::object_iterate_careful(ObjectClosureCareful* cl) {
guarantee(false, "NYI");
return bottom();
}
HeapWord* Space::object_iterate_careful_m(MemRegion mr,
ObjectClosureCareful* cl) {
guarantee(false, "NYI");
return bottom();
}
void Space::object_iterate_mem(MemRegion mr, UpwardsObjectClosure* cl) {
assert(!mr.is_empty(), "Should be non-empty");
// We use MemRegion(bottom(), end()) rather than used_region() below
// because the two are not necessarily equal for some kinds of
// spaces, in particular, certain kinds of free list spaces.
// We could use the more complicated but more precise:
// MemRegion(used_region().start(), round_to(used_region().end(), CardSize))
// but the slight imprecision seems acceptable in the assertion check.
assert(MemRegion(bottom(), end()).contains(mr),
"Should be within used space");
HeapWord* prev = cl->previous(); // max address from last time
if (prev >= mr.end()) { // nothing to do
return;
}
// This assert will not work when we go from cms space to perm
// space, and use same closure. Easy fix deferred for later. XXX YSR
// assert(prev == NULL || contains(prev), "Should be within space");
bool last_was_obj_array = false;
HeapWord *blk_start_addr, *region_start_addr;
if (prev > mr.start()) {
region_start_addr = prev;
blk_start_addr = prev;
// The previous invocation may have pushed "prev" beyond the
// last allocated block yet there may be still be blocks
// in this region due to a particular coalescing policy.
// Relax the assertion so that the case where the unallocated
// block is maintained and "prev" is beyond the unallocated
// block does not cause the assertion to fire.
assert((BlockOffsetArrayUseUnallocatedBlock &&
(!is_in(prev))) ||
(blk_start_addr == block_start(region_start_addr)), "invariant");
} else {
region_start_addr = mr.start();
blk_start_addr = block_start(region_start_addr);
}
HeapWord* region_end_addr = mr.end();
MemRegion derived_mr(region_start_addr, region_end_addr);
while (blk_start_addr < region_end_addr) {
const size_t size = block_size(blk_start_addr);
if (block_is_obj(blk_start_addr)) {
last_was_obj_array = cl->do_object_bm(oop(blk_start_addr), derived_mr);
} else {
last_was_obj_array = false;
}
blk_start_addr += size;
}
if (!last_was_obj_array) {
assert((bottom() <= blk_start_addr) && (blk_start_addr <= end()),
"Should be within (closed) used space");
assert(blk_start_addr > prev, "Invariant");
cl->set_previous(blk_start_addr); // min address for next time
}
}
bool Space::obj_is_alive(const HeapWord* p) const {
assert (block_is_obj(p), "The address should point to an object");
return true;
}
void ContiguousSpace::object_iterate_mem(MemRegion mr, UpwardsObjectClosure* cl) {
assert(!mr.is_empty(), "Should be non-empty");
assert(used_region().contains(mr), "Should be within used space");
HeapWord* prev = cl->previous(); // max address from last time
if (prev >= mr.end()) { // nothing to do
return;
}
// See comment above (in more general method above) in case you
// happen to use this method.
assert(prev == NULL || is_in_reserved(prev), "Should be within space");
bool last_was_obj_array = false;
HeapWord *obj_start_addr, *region_start_addr;
if (prev > mr.start()) {
region_start_addr = prev;
obj_start_addr = prev;
assert(obj_start_addr == block_start(region_start_addr), "invariant");
} else {
region_start_addr = mr.start();
obj_start_addr = block_start(region_start_addr);
}
HeapWord* region_end_addr = mr.end();
MemRegion derived_mr(region_start_addr, region_end_addr);
while (obj_start_addr < region_end_addr) {
oop obj = oop(obj_start_addr);
const size_t size = obj->size();
last_was_obj_array = cl->do_object_bm(obj, derived_mr);
obj_start_addr += size;
}
if (!last_was_obj_array) {
assert((bottom() <= obj_start_addr) && (obj_start_addr <= end()),
"Should be within (closed) used space");
assert(obj_start_addr > prev, "Invariant");
cl->set_previous(obj_start_addr); // min address for next time
}
}
#if INCLUDE_ALL_GCS
#define ContigSpace_PAR_OOP_ITERATE_DEFN(OopClosureType, nv_suffix) \
\
void ContiguousSpace::par_oop_iterate(MemRegion mr, OopClosureType* blk) {\
HeapWord* obj_addr = mr.start(); \
HeapWord* t = mr.end(); \
while (obj_addr < t) { \
assert(oop(obj_addr)->is_oop(), "Should be an oop"); \
obj_addr += oop(obj_addr)->oop_iterate(blk); \
} \
}
ALL_PAR_OOP_ITERATE_CLOSURES(ContigSpace_PAR_OOP_ITERATE_DEFN)
#undef ContigSpace_PAR_OOP_ITERATE_DEFN
#endif // INCLUDE_ALL_GCS
void ContiguousSpace::oop_iterate(ExtendedOopClosure* blk) {
if (is_empty()) return;
HeapWord* obj_addr = bottom();
HeapWord* t = top();
// Could call objects iterate, but this is easier.
while (obj_addr < t) {
obj_addr += oop(obj_addr)->oop_iterate(blk);
}
}
void ContiguousSpace::oop_iterate(MemRegion mr, ExtendedOopClosure* blk) {
if (is_empty()) {
return;
}
MemRegion cur = MemRegion(bottom(), top());
mr = mr.intersection(cur);
if (mr.is_empty()) {
return;
}
if (mr.equals(cur)) {
oop_iterate(blk);
return;
}
assert(mr.end() <= top(), "just took an intersection above");
HeapWord* obj_addr = block_start(mr.start());
HeapWord* t = mr.end();
// Handle first object specially.
oop obj = oop(obj_addr);
SpaceMemRegionOopsIterClosure smr_blk(blk, mr);
obj_addr += obj->oop_iterate(&smr_blk);
while (obj_addr < t) {
oop obj = oop(obj_addr);
assert(obj->is_oop(), "expected an oop");
obj_addr += obj->size();
// If "obj_addr" is not greater than top, then the
// entire object "obj" is within the region.
if (obj_addr <= t) {
obj->oop_iterate(blk);
} else {
// "obj" extends beyond end of region
obj->oop_iterate(&smr_blk);
break;
}
};
}
void ContiguousSpace::object_iterate(ObjectClosure* blk) {
if (is_empty()) return;
WaterMark bm = bottom_mark();
object_iterate_from(bm, blk);
}
// For a continguous space object_iterate() and safe_object_iterate()
// are the same.
void ContiguousSpace::safe_object_iterate(ObjectClosure* blk) {
object_iterate(blk);
}
void ContiguousSpace::object_iterate_from(WaterMark mark, ObjectClosure* blk) {
assert(mark.space() == this, "Mark does not match space");
HeapWord* p = mark.point();
while (p < top()) {
blk->do_object(oop(p));
p += oop(p)->size();
}
}
HeapWord*
ContiguousSpace::object_iterate_careful(ObjectClosureCareful* blk) {
HeapWord * limit = concurrent_iteration_safe_limit();
assert(limit <= top(), "sanity check");
for (HeapWord* p = bottom(); p < limit;) {
size_t size = blk->do_object_careful(oop(p));
if (size == 0) {
return p; // failed at p
} else {
p += size;
}
}
return NULL; // all done
}
#define ContigSpace_OOP_SINCE_SAVE_MARKS_DEFN(OopClosureType, nv_suffix) \
\
void ContiguousSpace:: \
oop_since_save_marks_iterate##nv_suffix(OopClosureType* blk) { \
HeapWord* t; \
HeapWord* p = saved_mark_word(); \
assert(p != NULL, "expected saved mark"); \
\
const intx interval = PrefetchScanIntervalInBytes; \
do { \
t = top(); \
while (p < t) { \
Prefetch::write(p, interval); \
debug_only(HeapWord* prev = p); \
oop m = oop(p); \
p += m->oop_iterate(blk); \
} \
} while (t < top()); \
\
set_saved_mark_word(p); \
}
ALL_SINCE_SAVE_MARKS_CLOSURES(ContigSpace_OOP_SINCE_SAVE_MARKS_DEFN)
#undef ContigSpace_OOP_SINCE_SAVE_MARKS_DEFN
// Very general, slow implementation.
HeapWord* ContiguousSpace::block_start_const(const void* p) const {
assert(MemRegion(bottom(), end()).contains(p),
err_msg("p (" PTR_FORMAT ") not in space [" PTR_FORMAT ", " PTR_FORMAT ")",
p, bottom(), end()));
if (p >= top()) {
return top();
} else {
HeapWord* last = bottom();
HeapWord* cur = last;
while (cur <= p) {
last = cur;
cur += oop(cur)->size();
}
assert(oop(last)->is_oop(),
err_msg(PTR_FORMAT " should be an object start", last));
return last;
}
}
size_t ContiguousSpace::block_size(const HeapWord* p) const {
assert(MemRegion(bottom(), end()).contains(p),
err_msg("p (" PTR_FORMAT ") not in space [" PTR_FORMAT ", " PTR_FORMAT ")",
p, bottom(), end()));
HeapWord* current_top = top();
assert(p <= current_top,
err_msg("p > current top - p: " PTR_FORMAT ", current top: " PTR_FORMAT,
p, current_top));
assert(p == current_top || oop(p)->is_oop(),
err_msg("p (" PTR_FORMAT ") is not a block start - "
"current_top: " PTR_FORMAT ", is_oop: %s",
p, current_top, BOOL_TO_STR(oop(p)->is_oop())));
if (p < current_top) {
return oop(p)->size();
} else {
assert(p == current_top, "just checking");
return pointer_delta(end(), (HeapWord*) p);
}
}
// This version requires locking.
inline HeapWord* ContiguousSpace::allocate_impl(size_t size,
HeapWord* const end_value) {
// In G1 there are places where a GC worker can allocates into a
// region using this serial allocation code without being prone to a
// race with other GC workers (we ensure that no other GC worker can
// access the same region at the same time). So the assert below is
// too strong in the case of G1.
assert(Heap_lock->owned_by_self() ||
(SafepointSynchronize::is_at_safepoint() &&
(Thread::current()->is_VM_thread() || UseG1GC)),
"not locked");
HeapWord* obj = top();
if (pointer_delta(end_value, obj) >= size) {
HeapWord* new_top = obj + size;
set_top(new_top);
assert(is_aligned(obj) && is_aligned(new_top), "checking alignment");
return obj;
} else {
return NULL;
}
}
// This version is lock-free.
inline HeapWord* ContiguousSpace::par_allocate_impl(size_t size,
HeapWord* const end_value) {
do {
HeapWord* obj = top();
if (pointer_delta(end_value, obj) >= size) {
HeapWord* new_top = obj + size;
HeapWord* result = (HeapWord*)Atomic::cmpxchg_ptr(new_top, top_addr(), obj);
// result can be one of two:
// the old top value: the exchange succeeded
// otherwise: the new value of the top is returned.
if (result == obj) {
assert(is_aligned(obj) && is_aligned(new_top), "checking alignment");
return obj;
}
} else {
return NULL;
}
} while (true);
}
// Requires locking.
HeapWord* ContiguousSpace::allocate(size_t size) {
return allocate_impl(size, end());
}
// Lock-free.
HeapWord* ContiguousSpace::par_allocate(size_t size) {
return par_allocate_impl(size, end());
}
void ContiguousSpace::allocate_temporary_filler(int factor) {
// allocate temporary type array decreasing free size with factor 'factor'
assert(factor >= 0, "just checking");
size_t size = pointer_delta(end(), top());
// if space is full, return
if (size == 0) return;
if (factor > 0) {
size -= size/factor;
}
size = align_object_size(size);
const size_t array_header_size = typeArrayOopDesc::header_size(T_INT);
if (size >= (size_t)align_object_size(array_header_size)) {
size_t length = (size - array_header_size) * (HeapWordSize / sizeof(jint));
// allocate uninitialized int array
typeArrayOop t = (typeArrayOop) allocate(size);
assert(t != NULL, "allocation should succeed");
t->set_mark(markOopDesc::prototype());
t->set_klass(Universe::intArrayKlassObj());
t->set_length((int)length);
} else {
assert(size == CollectedHeap::min_fill_size(),
"size for smallest fake object doesn't match");
instanceOop obj = (instanceOop) allocate(size);
obj->set_mark(markOopDesc::prototype());
obj->set_klass_gap(0);
obj->set_klass(SystemDictionary::Object_klass());
}
}
void EdenSpace::clear(bool mangle_space) {
ContiguousSpace::clear(mangle_space);
set_soft_end(end());
}
// Requires locking.
HeapWord* EdenSpace::allocate(size_t size) {
return allocate_impl(size, soft_end());
}
// Lock-free.
HeapWord* EdenSpace::par_allocate(size_t size) {
return par_allocate_impl(size, soft_end());
}
HeapWord* ConcEdenSpace::par_allocate(size_t size)
{
do {
// The invariant is top() should be read before end() because
// top() can't be greater than end(), so if an update of _soft_end
// occurs between 'end_val = end();' and 'top_val = top();' top()
// also can grow up to the new end() and the condition
// 'top_val > end_val' is true. To ensure the loading order
// OrderAccess::loadload() is required after top() read.
HeapWord* obj = top();
OrderAccess::loadload();
if (pointer_delta(*soft_end_addr(), obj) >= size) {
HeapWord* new_top = obj + size;
HeapWord* result = (HeapWord*)Atomic::cmpxchg_ptr(new_top, top_addr(), obj);
// result can be one of two:
// the old top value: the exchange succeeded
// otherwise: the new value of the top is returned.
if (result == obj) {
assert(is_aligned(obj) && is_aligned(new_top), "checking alignment");
return obj;
}
} else {
return NULL;
}
} while (true);
}
HeapWord* OffsetTableContigSpace::initialize_threshold() {
return _offsets.initialize_threshold();
}
HeapWord* OffsetTableContigSpace::cross_threshold(HeapWord* start, HeapWord* end) {
_offsets.alloc_block(start, end);
return _offsets.threshold();
}
OffsetTableContigSpace::OffsetTableContigSpace(BlockOffsetSharedArray* sharedOffsetArray,
MemRegion mr) :
_offsets(sharedOffsetArray, mr),
_par_alloc_lock(Mutex::leaf, "OffsetTableContigSpace par alloc lock", true)
{
_offsets.set_contig_space(this);
initialize(mr, SpaceDecorator::Clear, SpaceDecorator::Mangle);
}
#define OBJ_SAMPLE_INTERVAL 0
#define BLOCK_SAMPLE_INTERVAL 100
void OffsetTableContigSpace::verify() const {
HeapWord* p = bottom();
HeapWord* prev_p = NULL;
int objs = 0;
int blocks = 0;
if (VerifyObjectStartArray) {
_offsets.verify();
}
while (p < top()) {
size_t size = oop(p)->size();
// For a sampling of objects in the space, find it using the
// block offset table.
if (blocks == BLOCK_SAMPLE_INTERVAL) {
guarantee(p == block_start_const(p + (size/2)),
"check offset computation");
blocks = 0;
} else {
blocks++;
}
if (objs == OBJ_SAMPLE_INTERVAL) {
oop(p)->verify();
objs = 0;
} else {
objs++;
}
prev_p = p;
p += size;
}
guarantee(p == top(), "end of last object must match end of space");
}
size_t TenuredSpace::allowed_dead_ratio() const {
return MarkSweepDeadRatio;
}
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